Abstract: In order to solve the power backflow and power quality problems of the distribution grid caused by the increasing renewable energy generation and load decentralized integration, a meshed hybrid distribution grid structure based on low-frequency medium-voltage alternating current (LF-MVac) interconnection is proposed. On the basis of realizing power flow regulation, the proposed structure also has the advantages of flexible networking capabilities and better utilization of existing infrastructure. Moreover, an isolated modular multilevel matrix conversion device (I-M3C) is designed. The topology and modulation strategy are given, the average circuit model of I-M3C is established, and the control strategy of I-M3C based on double-dq coordinate transformation is designed. The energy conversion among the three ports of medium-voltage alternating current (MVac), LF-MVac and low-voltage direct current (LVdc) is realized. Finally, a meshed hybrid microgrid simulation platform based on LF-MVac interconnection is built, which proves the effectiveness of the proposed key equipment and the correctness of relevant theoretical analysis.